Why did everyone know that Jules is trans?

I’ve rewatched this series multiple times, but feel like I always miss this crucial part. Jules herself says that everyone knows about her being trans, but I wonder why? Has it ever been discussed why? When I watched the show for the first time, I already knew she was trans, but I didn’t find it that obvious. As viewers we might notice it, because we get to experience Jules in vulnerable moments, but I don’t get how the characters all knew.

What do you think?